This application is based on patent application Ser. No. 2000-48328 filed Feb. 24, 2000 in Japan, the content of which is incorporated hereinto by reference.
1. Field of the Invention
The present invention relates to an inkjet printing apparatus for printing on a printing medium by using a printing head for ejecting ink and is particularly squitable to be applied to maintenance of the printing head.
2. Description of the Related Art
There are inkjet printing apparatuses in which printing heads can be exchanged appropriately according to the purpose of print such as print of monochrome image, color image, binary image, half-tone image or photo-tone image and so on, in addition to exchange when the life of printing head (inkjet head) ends. Also, they are so constructed that printing agent can be replenished, e.g. by means of exchange of ink tank, when ink as printing agent runs out.
When the printing head is exchanged, ejection failure or non-ejection might be caused by clogging of an ink ejection opening depending on the storage condition of the printing head. Also, when the ink tank is exchanged, ejection failure or non-ejection might occur because a liquid chamber in the printing head or a liquid passage from the liquid chamber to the ejection opening is not fully filled with ink, or air is mixed in the passage from the ink tank to the liquid chamber of the printing head.
In general, in the inkjet printing apparatus, recovery processing means for forcedly discharging ink through the ink ejection opening is provided in order to eliminate the cause of ejection failure or non-ejection and to maintain the ejection performance favorable. The recovery processing means comprises, for example, a cap member for capping a face on which ejection openings are formed of the inkjet head (the face will be referred as xe2x80x98the ejection opening forming facexe2x80x99, hereinafter), suction means for suctioning the inside of the cap and a member for wiping the ejection opening forming face.
In conventional inkjet printing apparatuses, when it is determined that the printing head or the ink tank should be exchanged, the recovery operation is executed each time using the recovery processing means.
The recovery processing for forcedly discharging ink through the inkjet head by such suction or the like is the processing indispensable for eliminating ejection failure or the like of the inkjet head due to clogging of the ink ejection opening and for maintaining ejection performance. However, it encompasses a problem that ink consumption will rise due to recovery processing and therefore, it is desirable that the processing is preferably kept within the necessary and sufficient range.
However, in the conventional inkjet printing apparatus, the recovery processing is executed in the condition not accompanied actual print, and ink is wasted in some cases. For example, it occurs in the case that a printing head not suitable for the print purpose is attached. Also, in a printing apparatus which judges that replacement of an ink tank is executed by detecting an opening operation of a front cover and so on provided for the replacement or a replacement switch pressing operation, recovery processing is executed each judgement, and ink would be wasted by recovery operation more than necessary.
Thus, the object of the present invention is to effectively suppress increase in ink consumption by properly judging necessity of recovery processing while maintaining ejection quality of the inkjet head.
In a first aspect of the present invention, there is provided an inkjet printing apparatus for printing on a printing medium by using a printing head for ejecting ink, comprising:
means for executing recovery processing for making ink ejection state of the ink favorable;
means for storing information showing whether the recovery processing is necessary or not; and
control means for judging necessity of the recovery processing based on the contents of the storing means prior to start of print operation and for executing the recovery processing when it is judged that the recovery processing is necessary.
In a second aspect of the present invention, there is provided a printing system comprising a printing apparatus for performing printing on a printing medium by using a printing head and an image data supplying apparatus for supplying an image data to be printed to the printing apparatus, the apparatus having means for executing recovery processing for making ink ejection state of the ink favorable, the system comprising:
means for storing information showing whether the recovery processing is necessary or not; and
control means for judging necessity of the recovery processing based on the contents of the storing means prior to start of print operation and for executing the recovery processing when it is judged that the recovery processing is necessary.
According to the present invention, particularly its one preferred embodiment, which will be described later, an exchange mode of printing head/ink tank (ink storing member) is provided as well as exchange detecting means, a temporary memory (storage means) and a non-volatile memory (holding means) for storing necessity of a suction recovery processing judged based on the detected results, and suction recovery executing means (control means) for determining the necessity of suction recovery of the printing head based on the memory contents before print and for executing suction recovery if necessary. Further, there is provided a function to write predetermined information in the above memory and the non-volatile memory after execution of the suction recovery.
When it is judged that suction recovery of the printing head is necessary due to exchange of the printing head or the ink tank, the information is stored in the temporary memory and the non-volatile memory mounted on the printing apparatus. Only before execution of the print operation, it is judged whether the suction recovery is necessary or not, if an affirmative judgment is made, the suction recovery operation is executed. At execution of the suction recovery, the above information is cleared. Also, the above information is stored in the non-volatile memory and its contents are retained even after the apparatus power source (primary power supply) is off, and necessity of maintenance processing after the power supply is turned on can be judged based on the maintenance state of the printing head before the power supply was turned off. By them, increase in ink consumption due to recovery processing of the inkjet head is effectively suppressed while maintaining ejection quality of the printing head.
Incidentally, in this specification, a word xe2x80x9cimagexe2x80x9d means the concept covering characters such as letters, numbers, symbols, etc. as well as images of patterns, pictures, photos, etc. in a narrow sense and also includes mixture of them.
A word xe2x80x9cprintxe2x80x9d refers to not only forming significant information, such as characters and figures, but also forming images, designs or patterns on printing medium and processing media, whether the information is significant or insignificant or whether it is visible so as to be perceived by humans.
The term xe2x80x9cprinting mediumxe2x80x9d include not only paper used in common printing apparatus, but cloth, plastic films, metal plates, glass, ceramics, wood, leather or any other material that can receive ink.
Further, the word xe2x80x9cinkxe2x80x9d should be interpreted in its wide sense as with the word xe2x80x9cprintxe2x80x9d and refers to liquid that is applied to the printing medium to form images, designs or patterns, process the printing medium or process ink.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.